A luminaire can comprise a frame that provides a cavity for emitting illumination towards a space to be illuminated. A light source, such as a row of light emitting diodes, can emit light into the cavity. The cavity can extend lengthwise between two end caps of the frame that are located at opposing ends of the luminaire. The frame can further comprise two bridges that are located adjacent the end caps, one at each end of the frame. Two rails that extend on opposing sides of the cavity can connect the two bridges to one another. A system of grooves and protrusions can interlock the rails to the bridges. A system of standardized interchangeable components that facilitates rapid manufacture of custom luminaires can comprise the bridges, the rails, and the end caps.